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Biomedical subjects

H Iwanaga

Publications and source records attributed to H Iwanaga.

At least 19 recordsLinked to original sources
PubMed2001

Development of a new calcium phosphate cement that contains sodium calcium phosphate.

A cement powder consisting of sodium calcium phosphate, Na3Ca6(PO4)5, in addition to tetracalcium phosphate and beta-tricalcium phosphate was prepared by pulverizing blocks of 4 wt% sodium-, 11 wt% carbonate-containing apatite samples that were heated at 1700 degrees C for 5 h. When mixed with 30 wt% malic acid or citric acid at a powder liquid ratio of 3:1, the cement set in 3 or 7 min at room temperature with compressive strength being around 52 or 27 MPa. In HeLa-cell cultures, the cement mixed with malic acid was less cytotoxic than the cement mixed with citric acid, which was far less cytotoxic than a commercial carboxylate cement used as a negative control, suggesting malic acid to be superior to citric acid as a liquid in this regard. Similar findings were also obtained with osteoclasts, of which culture experiments clearly suggested that the number of osteoclasts on the cement mixed with malic acid was significantly greater than that on the cement mixed with citric acid. Since osteoclastic response to substrates could be used as a maker in evaluating their bioresorbability associated with osteoclasts, the above finding may suggest that the cement that is to be mixed with malic acid would be more useful as bone substitutes.

Animals↗
PubMed2001

[Lambert-Eaton myasthenic syndrome: diagnosis and treatment].

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder of neuromuscular and autonomic transmission in which IgG autoantibodies lead to presynaptic voltage-gated calcium channel (VGCC) loss, or as a paraneoplastic disorder in association with small cell lung carcinoma (SCLC). Recent results strongly suggest that the antibodies to P/Q-type VGCC are the principal pathogenic factors in LEMS. Here, we present diagnosis and treatment of LEMS patients. Proximal weakness, depressed tendon reflexes, autonomic symptoms, and electrical posttetanic potentiation together are essential to accurately diagnose LEMS. The diagnosis is established immunologically by the presence of anti-P/Q-type VGCC antibodies, detected using the (125)I-omega-conotoxin MVIIC radioimmunoassay, which will be present in 85% of LEMS patients. The drug 3,4-diaminopyridine with anti-cholinesterase inhibitor is most effective in LEMS patients with or without SCLC. In LEMS with SCLC, specific tumor therapy will often improve the neurological disorder. In some cases plasmapheresis or intravenous immunoglobulin may be indicated.

English Abstract↗
PubMed2000

Ultramicroanalysis of reducing carbohydrates by capillary electrophoresis with laser-induced fluorescence detection as 7-nitro-2,1,3-benzoxadiazole-tagged N-methylglycamine derivatives.

A method for ultramicroanalysis of carbohydrates using capillary electrophoresis with laser-induced fluorescence detection was developed, based on precapillary conversion to 7-nitro-2,1, 3-benzoxadiazole (NBD)-tagged N-methylglycamines. Although the derivatization involves two-step reactions, i.e., reductive N-methylamination followed by condensation with NBD-F, they can be carried out in a one-pot fashion and proceed quantitatively within ca. 50 min in total. Since the reaction conditions are mild, it does not cause desialylation. The derivatives can be well separated by capillary electrophoresis and sensitively detected by argon laser-induced fluorescence. It allowed detection of monosaccharides of down to nanomolar concentrations for analytical sample solution, which correspond to the attomole injected amounts, and good linearity was observed over a wide range. It was also successfully applied to analysis of N-glycans in a microgram quantity of a glycoprotein. Studies on the cleanup of derivatized product are also described in relation to N-glycan analysis.

4-Chloro-7-nitrobenzofurazan↗
PubMed2000

Use of glass slides coated with apatite-collagen complexes for measurement of osteoclastic resorption activity.

This study was designed to evaluate the use of apatite-collagen complexes (ACC) coated onto glass slides for measurement of osteoclastic resorption activity. ACC-coated glass slides were prepared by immersion in beta-glycerophosphate solution for 7-14 days after glass slides coated with type I collagen had been treated with alkaline phosphatase and phosvitin. Osteoclast-containing cell suspensions were prepared from the long bones of 1-day-old rabbits and were seeded in medium 199 (containing 10% FBS) onto ACC-coated glass slides. After allowing the cells to attach for 1.5 h, the glass slides were incubated for periods of up to 96 h. The cells were observed by scanning electron microscopy and cytochemically for tartarate resistant acid phosphatase (TRAP) activity. Some slides were treated with FITC-phalloidin and anti-type I collagen antibody. TRAP-positive multinucleated cells were located in transparent spaces on the glass slides. These spaces did not stain immunohistochemically with anti-type I collagen antibody. Podosome formation was observed in the multinucleated cells facing the edge of the transparent spaces. The scanning electron microscopy demonstrated well-spread large cells located on the flattened surface on apatite particles covering the glass surface. Our results suggest that osteoclasts could resorb the apatite particles and coated collagen on the glass slide. The resorption lacunae appeared as transparent spaces, and the cytoskeleton of resorbing osteoclasts was observed in these spaces. ACC-coated glass slides could be useful for investigating the function and metabolic activities of osteoclasts.

Animals↗
PubMed1999

Osteoclastic responses to various calcium phosphates in cell cultures.

Disks made of hydroxyapatite, beta-tricalcium phosphate, carbonate apatite, tetracalcium phosphate, alpha-tricalcium phosphate, dicalcium phosphate dihydrate, and octacalcium phosphate were incubated in osteoclastic cell cultures for 2 days. The first five salts were sintered and the last two were compressed before incubation. Osteoclasts resorbed only the sintered carbonate apatite disks. However, osteoclasts were able to resorb octacalcium phosphate disks that were preincubated for 1 day in medium without cells, indicating that surface conditioning was important for osteoclastic resorption of this calcium phosphate. Although resorption did not occur, medium calcium and phosphorus changed to an appreciable extent after a 2-day incubation of beta-tricalcium phosphate, tetracalcium phosphate, alpha-tricalcium phosphate, and dicalcium phosphate dihydrate. These changes in the medium calcium and phosphate concentrations could explain why osteoclasts appeared to have lost their activity on these calcium phosphate disks and were not capable of resorbing them. With hydroxyapatite disks no changes were observed in the medium calcium and phosphorus before and after incubation. Moreover, the osteoclasts appeared to be essentially the same as with the sintered carbonate apatite disks and with bone slices used as a control. Nevertheless, no pits or lacunae were observed on the hydroxyapatite disks, indicating that sintered carbonate apatite should be superior to sintered hydroxyapatite as a bioresorbable bone substitute.

Animals↗
PubMed1997

Setting properties of alginate impression materials in dynamic viscoelasticity.

The viscoelastic properties of three alginate impression materials were investigated. A landmark of working time was calculated using a raw phase-time curve. A landmark of setting time was calculated from an inflection point of the divided difference of the first order in the share modulus-time curve. As a result, the working time was common at the point of delta = 45 degrees in variable frequencies. The mean value was obtained with less deviation. The setting times obtained were similar for variable frequencies. The mean values showed a distinct difference for each impression material.

Alginates↗
PubMed1996

Clinical features of the haemorrhage type moyamoya disease based on 31 cases.

We evaluated and analysed our own 31 cases of the haemorrhagic type of moyamoya disease to clarify the clinical features of this disease. The cases were divided into three groups. Group A consisted of 12 cases with aneurysms. Aneurysms on the circle of Willis were treated as ordinary saccular aneurysms. Group B consisted of 14 cases with intracerebral haemorrhage (ICH) without aneurysms. These were managed almost as spontaneous ICH. Group C consisted of 5 cases with intraventricular haemorrhage (IVH) without aneurysms or ICH. Twenty-two surgical procedures for aneurysms, ICH and IVH were done in 19 cases (62%). Nineteen procedures for preventing future strokes were undertaken in 11 cases (35%). The overall initial outcome was excellent in 12 cases (39%), good in 7 cases (23%), poor in 7 cases (23%), and death in 5 cases (15%). During the follow-up period (mean: 6.5 years), rebleeding occurred in two cases (8%), and ischaemic attacks in two cases (8%). The rate of rebleeding or ischaemic attacks was 1.19% per patient-year during the follow-up period. There was no ischaemic or rebleeding episode in cases treated by STA-MCA bypass with encephalomyosynagiosis (EMS) during the follow-up period. Management of the primary haemorrhage should be according to the clinical condition, type of haemorrhage, and source of haemorrhage. When the patient needs to undergo revascularization surgery to prevent future strokes, we recommend STA-MCA bypass with EMS instead of encephaloduro-arteriosynangiosis (EDAS).

Adult↗
PubMed1995

Effects of intravenous nitroglycerin combined with dopamine on intracranial pressure and cerebral arteriovenous oxygen difference in patients with acute subarachnoid haemorrhage.

The effects of intravenous nitroglycerin (NTG) combined with dopamine on intracranial pressure (ICP) and cerebral arteriovenous oxygen difference (AVDO2) were studied in 11 patients with acute subarachnoid haemorrhage (SAH). The study was performed on Days 1 to 3 of SAH after aneurysmal clipping. Treatment consisted of an intravenous drip infusion of NTG in increasing incremental doses of 0.5, 1.0, 1.5, 2.0, and 2.5 micrograms/kg/min at one-hour intervals. Dopamine (5 to 10 micrograms/kg/min) was also given concurrently to maintain systemic blood pressure. ICP values before NTG administration ranged from 7 to 24 mmHg (mean. 11.91 +/- 5.30 mmHg). ICP began to increase immediately after the administration of NTG 0.5 microgram/kg/min and peaked at 14.64 +/- 5.93 mmHg 10 minutes after onset of infusion. Thereafter, ICP gradually returned to pretreatment levels. Increasing the dose of NTG failed to induce further significant rises in ICP. Mean AVDO2 before NTG administration was 4.69 +/- 0.62 ml/dl. This parameter showed no significant change during NTG infusion, although cerebral perfusion pressure decreased to between 75% to 94% of the control value after NTG administration. These results indicate that continuous NTG infusion combined with dopamine does not have adverse effects on ICP (the ICP increase is minimal and transient) and may even have beneficial effects on CBF in patients with acute SAH.

Adult↗
PubMed1995

Factors influencing gelation time of tissue conditioners.

To investigate the effects of the composition and structure on the gelation of tissue conditioners, we measured gelation time with an oscillating rheometer. Also, the plasticizer factor was determined using linear multiple regression equations with the dependent variable of gelation time and the independent variables of molecular weight, molar volume, solubility parameter and viscosity of plasticizers. The results obtained were (i) gelation time decreased as the average particle size of poly-ethyl-methacrylate was decreased and its weight average molecular weight increased; (ii) gelation time decreased as ethanol content in the liquid increased. It varied depending on the type of plasticizer; (iii) it was suggested that gelation time was explained by linear multiple regression equations with independent variable of molar volume, solubility parameter and viscosity of plasticizer. In particular, the most influential factor was suggested to be molar volume.

Ethanol↗
PubMed1995

[A huge idiopathic brain stone in the posterior fossa].

We report a case of idiopathic brain stone occurring in the posterior fossa. A 72-year-old woman with a huge calcified mass in the posterior fossa on plain craniogram was referred to us. She had suffered from intractable tinnitus and mild cerebellar ataxia for twenty years. CT scan revealed a dense bony mass in the posterior fossa. Angiogram only showed an avascular huge mass in the posterior fossa. MRI clearly revealed the shape, heterogenous composition and anatomical relation to the surrounding structure of the mass. The mass was totally removed uneventfully under ABR and SEP monitoring. The patient was discharged with improvement of subjective symptoms. The mass was histologically diagnosed as an idiopathic brain stone because its components were mainly calcified tissues and collagen fiber of unknown etiology; no viable cells were found in any of the specimens. Idiopathic brain stones are very rare and only eight cases have been reported in the literature. The etiology and clinical symptoms of this condition are briefly discussed.

Aged↗
PubMed1995

Clinicopathological study on pineocytoma.

Six cases of pineocytoma, which had developed in the parenchyma of the adult pineal body, were examined immunohistochemically and under an electron microscope, after the malignancy of each case had been determined using our classification. One case was rated as grade 1 showing a lobular structure and resembling the normal pineal body. Two cases were rated as grade 2 without a lobular structure but with pineocytomatous rosettes (P-rosettes). Two cases were rated as grade 3 without P-rosettes but with few mitotic figures. One case was rated as grade 4 with marked cellular pleomorphism, numerous mitotic figures and necrotic foci. When examined immunohistochemically, neuron-specific enolase was positive but glial fibrillary acidic protein was negative in all cases. Under an electron microscope, all cases showed abortive synapses, and clear or dense core vesicles. These findings allow us to make two conclusions. First, pineocytoma is always a tumor of neuronal lineage, regardless of their grade of malignancy. Second, the grade 4 pineocytoma should be distinguished from the type of tumor classically called "pineoblastoma." That is, the former seems to be a biologically dedifferentiated tumor, while the latter seems to be biologically undifferentiated tumor.

Adult↗
PubMed1995

[Dural AVF of the posterior fossa associated with sinus occlusion presenting as intracerebral hemorrhage: case report].

A 69-year-old man was admitted because of sudden onset of consciousness disturbance. Neurological examination on admission revealed slightly disturbed consciousness, sensory aphasia and right hemiparesis. CT scan disclosed a hematoma in the left posterior temporal lobe. Left carotid angiograms showed dural AVF of the transverse/sigmoid sinus fed mainly by the left occipital and posterior auricular arteries. On the angiograms the left sigmoid sinus was completely occluded. This was associated with retrograde venous flow into the cortical veins, the superior petrosal sinus and the contralateral traverse sinus. After stabilizing the condition, we totally resected the dural AVF including the left transverse sinus. The postoperative course was uneventful. Histopathological examination of the surgically resected specimen revealed that the dural A-V fistula per se existed in the sinus wall.

Aged↗
PubMed1994

Management of dissecting aneurysms of the posterior circulation.

We analysed the clinical presentation, treatment and outcome of our own 36 cases of posterior circulation dissecting aneurysms (DA) and discussed the surgical indications and procedures regarding posterior fossa DA. Twenty one cases were male, 15 cases were female. Their mean age was 54 +/- 14 years. Clinical manifestations were subarachnoid haemorrhage (SAH) in 14 cases (39%) and ischaemic attacks in 22 cases (61%). Three of 14 SAH cases had rebleeding in the acute stage. Angiographic findings were aneurysmal dilatation in 16 cases, retention of contrast medium in 12 cases, string sign in 9 cases, double lumen in 4 cases, pearl and string sign in 3 cases, and occlusion of parent artery in 2 cases. Surgical treatment was performed on nineteen cases (53%). The operation was carried out in the acute stage on the SAH group; in the subacute or chronic stage on the ischaemic group. The surgical procedure was the proximal ligation, trapping and removal of DA with or without revascularization of the parent artery. 84% of the surgically managed patients and 71% of the nonsurgical cases had a favourable outcome (good recovery or moderate disability). Poor prognosis was revealed from the rebleeding and primary neurological stage. We recommend surgical treatment in the acute stage on the SAH group. On the ischaemic group surgical treatment in the subacute or chronic stage is recommended, if the DA has the risk of rupture or progression of the dissection.

Adolescent↗
PubMed1994

Effects of superficial temporal to middle cerebral artery bypass for ischaemic retinopathy due to internal carotid artery occlusion/stenosis.

The effects of superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis for retinopathy is discussed and analysed in 19 cases of occlusive internal carotid artery disease (4 with stenosis and 15 with occlusion) according to Doppler sonography (DS) of the retinal artery, optic fundi and visual impairment symptoms. Preoperatively, all cases showed abnormal DS findings (stenosis patterns in 2 cases and the reversed flow patterns in 17 cases). All cases showed ischaemic changes of the optic fundi. Visual symptoms were amaurosis fugax in 2 cases, decline of visual acuity in 13 cases and both in 4 cases. At one month after the bypass, two stenosis pattern cases showed almost normal DS findings. In the 17 reversed flow pattern cases, 13 cases had a marked improvement of the reversed flow. The ischaemic changes of the optic fundi were ameliorated in 12 cases. In the follow-up stage, greater improvement in the DS findings and the optic fundi could be seen in all cases. In all cases worsening of the visual acuity was prevented, and in some cases the decreased visual acuity improved. The above improvements correlated well with the improvement of DS findings. It is believed that this procedure should be performed to prevent and improve ischaemic retinopathy caused by ischaemic ICA lesion.

Aged↗
PubMed1994

Effects of denture cleansers on direct soft denture lining materials.

The deterioration of six commercial resilient denture lining materials immersed in seven groups of denture cleansers was investigated. Although the grades of deterioration of these soft liners were not related to the amount of peroxide content or the pH of denture cleansers, the effects of peroxide cleansers were, with few exceptions, more severe than those of the other types. For example, an enzyme cleanser caused severe changes of one soft liner. The grades of surface porosity were correlated well with the log of the gelation time of the tissue conditioners (except for one soft liner), in four kinds of peroxide cleansers. These results suggest that various components of denture cleansers and soft lining materials, particularly peroxides, in cleansers and gel formation components of soft liners play important roles in the deterioration of soft liners caused by cleansers.

Acrylic Resins↗
PubMed1994

Strategies to improve the outcome of carotid endarterectomy.

The outcomes of carotid endarterectomy (CEA) including long-term results in 121 patients (126 procedures) were retrospectively analyzed to identify the causes of operative morbidity. The angiographic internal carotid artery (ICA) stenosis was severe (> 70%) in 62 patients and moderate (50-70%) with ulceration in 64. The arterial wall was sutured primarily in 91 patients and with patch graft in 35. The outcomes 3 months after operation were good recovery in 86 patients, moderately disabled in 20, severely disabled in 11, and death in four. Three patients suffered operative morbidity (2.5%). During follow-up, three patients (2.6%) suffered transient ischemic attack on the operative side due to middle cerebral artery stenosis (50%) or ICA occlusion at the origin, and recurrent stenosis (40%) of the common carotid artery and ICA (1 each). In the latter two cases, the artery was primarily sutured. Improved therapeutic results require use of patch vein graft for the arterial wall suture, checking of the CEA patency, and prevention of intracranial ischemic events and hemorrhage due to associated lesions.

Adult↗